package MyLinkedList;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: tao
 * Date: 2023-12-31
 * Time: 13:22
 */
public class MyLinkedList implements Ilist{

    public ListNode head;

    static class ListNode{
        int val;
        ListNode next;

        public ListNode(int val) {
            this.val = val;
        }
    }

    public void createList() {
        ListNode node1 = new ListNode(12);
        ListNode node2 = new ListNode(23);
        ListNode node3 = new ListNode(34);
        ListNode node4 = new ListNode(45);
        ListNode node5 = new ListNode(56);
        node1.next = node2;
        node2.next = node3;
        node3.next = node4;
        node4.next = node5;
        this.head = node1;
    }

    @Override
    public void addFirst(int data) {
        ListNode node = new ListNode(data);
        if(this.head == null) {
            this.head = node;
        } else {
            node.next = this.head;
            this.head = node;
        }
    }

    @Override
    public void addLast(int data) {
        ListNode node = new ListNode(data);
        if(this.head == null) {
            this.head = node;
        } else {
            ListNode cur = this.head;
            while (cur.next != null) {
                cur = cur.next;
            }
            cur.next = node;
        }
    }

    @Override
    public void addIndex(int index, int data) {
        try {
            if(index < 0 || index > size()) {
                throw new IndexException("下标异常,下标:" + index);
            } else {
                if(index == 0) {
                    //头插
                    addFirst(data);
                    return;
                }
                if (index == size()) {
                    //尾插
                    addLast(data);
                    return;
                }
                ListNode node = new ListNode(data);
                ListNode cur = searchPrev(index);
                node.next = cur.next;
                cur.next = node;
            }
        } catch (IndexException e) {
            e.printStackTrace();
        }
    }
    //找到链表前一个的位置
    private ListNode searchPrev(int index) {
        ListNode cur = this.head;
        int count = 0;
        while (count != index - 1) {
            cur = cur.next;
            count++;
        }
        return cur;
    }

    @Override
    public boolean contains(int key) {
        ListNode cur = this.head;
        while (cur != null) {
            if(cur.val == key) {
                return true;
            }
            cur = cur.next;
        }
        return false;
    }

    @Override
    public void remove(int key) {
        if(this.head == null) {
            //一个节点都没有，无法删除
            return;
        }
        if(this.head.val == key) {
            this.head = this.head.next;
            return;
        }
        ListNode cur = findPrev(key);
        if(cur == null) {
            System.out.println("没有要删除的点");
        } else {
            ListNode del = cur.next;
            cur.next = del.next;
        }
    }

    private ListNode findPrev(int key) {
        ListNode cur = this.head;
        while (cur.next != null) {
            if(cur.next.val == key) {
                break;
            }
            cur = cur.next;
        }
        return cur == this.head ? null : cur;
    }

    @Override
    public void removeAllKey(int key) {
        if(this.head == null) {
            return;
        }
        ListNode prev = this.head;
        ListNode cur = this.head.next;
        while (cur != null) {
            if(cur.val == key) {
                prev.next =cur.next;
                cur = cur.next;
            } else {
                cur = cur.next;
                prev = prev.next;
            }
        }
        if(this.head.val == key) {
            this.head = this.head.next;
        }
    }

    @Override
    public int size() {
        int count = 0;
        ListNode cur = head;
        while (cur != null) {
            count++;
            cur = cur.next;
        }
        return count;
    }

    @Override
    public void clear() {
        ListNode cur = this.head;
        while (cur != null) {
            ListNode curNext = cur.next;
            cur.next = null;
            cur = curNext;
        }
        head = null;
    }

    @Override
    public void display() {
        ListNode cur = head;
        while (cur != null) {
            System.out.print(cur.val + " ");
            cur = cur.next;
        }
        System.out.println();
    }
}
